It's good to get to know a person very well before coming to conclusions on the kind of person that they are. I'm guilty of it too, there are times I judge people based on their first impressions and I was wrong, and there have been times that I've been right too.
Omo the way I judge people based on first impression needs to be studied, sometimes I say our spirit doesn't align and I find it hard to get to know them well
Getting to know people for ourselves is actually the best thing I would suggest we all do.
Just like you said I have judged based on first impression and sometimes I was right and sometimes am wrong too.